Thinking about buying a new GH4 or EM1

I currently have a G6 and I'm thinking about upgradingto either a GH4 or an EM1.I'm not interested in video, only stills which is mainly landscapes and close up nature shots. I do like taking panoramas but I don't mind the idea of manual ratherthan in camera.The question is simply is it a worth while upgrade or am I just spending my money for the sake of having a new toy to play with? What am I likely to gain out of it?